1. Field of the Invention
The present invention relates to laminations which are formed into lamination stacks and a transformer core assembly made by forcing two aligned stacks of the laminations into a tight mechanical engagement with each other.
2. Description of the Prior Art
Heretofore designs or configurations of laminations and lamination stacks for forming lamination transformer core assemblies have been proposed. Examples of several previously proposed laminations, lamination stacks and transformer core assemblies made therefrom are disclosed in the following U.S. patents:
______________________________________ U.S. Pat. No. Patentee ______________________________________ 1,512,032 Ledwinka 2,137,433 Wirz 3,587,020 Waasner 4,414,521 Reisem ______________________________________
Other examples are disclosed in the Kammeyer German Published Patent Application No. 2,139,010 and the Blum French Pat. No. 1,558,102.
The prior patent publications referred to above disclose a variety of lamination configurations including "E" laminations adapted to be formed in a stack and joined with a similar stack of "E" shaped laminations and transformers which include a stack of "E" shaped laminations fixed to a stack of "I" shaped laminations. Such prior art laminations and stacks formed thereby also include "F" shaped laminations where the interior leg of the "F" shaped lamination has an inclined surface for engaging and camming (or bearing) against a like inclined surface on an identical "F" shaped lamination (see Published German Patent Application No. 2,002,737).
Furthermore, some prior art laminations provide an end formation at the end of an outer leg of an "E" shaped lamination which has an inner surface, an outer surface and an "S" shaped surface connecting the inner and outer surfaces for engagement with a mating configuration on the side edge of an "I" shaped lamination (see French Pat. No. 1,558,102).
As will be described in greater detail hereinafter, the transformer core assembly of the prsent invention differs from previously proposed laminations, lamination stacks and core assemblies therefrom by providing lamination stacks having at least one stack of "E" shaped laminations with the middle leg of the "E" shaped lamination having an outer end formation including an outer surface, an inner surface and an inclined surface therebetween with the inclined surface on a mating stack of laminations ("I" or "E") being offset transversely of the elongate axis of the leg so that there is a transverse camming action when the stacks of laminations are joined together on this construction. The end formation on one outer leg of the "E" is identical to the end formation on the outer leg of the other leg of the "E" shaped lamination, with each such end formation including an outer surface, an inner surface and a generally "S" shaped surface therebetween adapted to engage and mate with a mating configuration on a side edge of an "I" lamination and with the inclined camming surfaces causing the mating " S" shaped surfaces on the side edge of the "I" lamination to be urged toward the respective "S" shaped surfaces on the end formations of the first and second outer legs of the "E" shaped lamination.
Additionally the pieces of lamination in each of the mating stacks of laminations are punched from the same area in a sheet of lamination blank material and the lamination pieces in one stack are arranged upside down relative to the pieces in the other stack so that the burr edge at the corner of each lamination in one stack is on one side of each lamination and the burr edge of each lamination on the other stack is on the other side so as to provide a better nesting or mating fit between the lamination stacks when they are forced together.
Furthermore, depressed areas are provided in the lamination stacks, either circular or rectangular in shape, so as to provide a recess on one side of each lamination and a detent on the other side of each lamination to facilitate interlocking engagement of the laminations when they are press fitted against each other.